Sound-producing diaphragm



H. FISCHER SOUND PRODUCING DIAPHRAGM March 4 1924.

Filed Got. 24, 1922 I INVENTOR 1W 7 W W ummq A TTOR NE 15 I plishes in lar The invention is based on the knowled e Patented Mar. 4, 1924.

UNITED'IHSTATESI PATENT orr cs.

W FISCHER, OF NEW YORK, N. Y., ASSIGK'OB '10 0. BRANDES, INC, 01' NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SOUND-PBODUCIN G DIA PmGI.

Application filed October 24, 1922. Serial No. 596,880.

To all whom it may concern:

Be it known that I, HERMANN FISCHER, a citizen of Russia, residing at New York, in the county of New York, State of New P York, have invented certain new and useful Improvements in Sound-Producing Diaphragms; and I do hereby declare the followmg to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. This. application is a continuation in part of my application Serial No. 575,246, led July 15, 1922.

The invention relates to sound producing diaphra and has for its object the provislon 0 an improved diaphragm whereby greater accurac in the reproduction -o' musical and ot er tones may be accomplished: More articularly, the object in view is to rovlde a diaphragm for use either in te ephones or talking machines, which will produce the lower notes of the musical scale in more'correct proportionate .volume, as compared to the volume of the higher notes, than can be obtained with the or inary diaphragm, such as is regularly used for telephone receivers.

When a diaphragm of, say, a telephone receiver is proportioned so as to have a natural period of the order of the hi her notes of the musical scale, it will repr uce these notes with com arative accurac but as is well known, the ower notes are und I. to be greatly attenuated. This, as is also well known, is due to the fact that the diaflphragm ofiors increasing inertia, as the di erence between the period of the forced vibrations and the natural period increases; 6 The resent invention takes account of this ina ility of the ordinary diaphragm to reproduce in proportionate volume both the up r and lower notes of the musical scale an provides a diaphrafin which accommeasure t e'object stated.

of the fact that the particular form of t e so-called f-holes in violins isa factor of vital importance-experience having shown that the best results a parently cannot be obtained in a violin wit any other form of opening. I

According to the preferred form of the invention, there is provided a sound producing diaphragmhavingone or more 1 -.holes.

Such a diaphragm, it has been found, gives 1 materially improved results.

The specific form of diaphragm shown in the accompanying drawing, and described hereinafter, is rovided with-two fholes and is adapted particularly for use in a single pole telephone receiver. The invention is not, however, limited to any particular number of f-holes, nor to the exact shape of f-holes shown.

In the drawing, Fig. 1 shows a diaphragm having two f-holes, in accordance with the preferred form of the invention, and Fi 2 is a cross sectional view of a single po e telephone receiver, of which the diaphragm of Fig. 1 forms a part.

The diaphragm indicated by reference character 1 is provided with two a ertures 1 and 1", WlllCh corresponds close y with the so-called fholes, usually provided in violins and some other musical instruments. According to the theory of action of this diaphragm, which is believed to be well founded, the lower notes of the musical scale are accentuated by the projecting por-. 'tions 1, 1", 1 and 1, which apparently have a lower natural period than the remainder of the diaphragm.

The essential element'of the invention resides in the provision of an aperture or apertures which define one or more projectingi. portions of-varying width,'1, 1, '1 an 1.

In'Fig. 2, there is shown a cross-sectional view of an ordiary single pole watch-case telephone receiver, including a diaphragm like that of Fig. 1.- In this figure, 2 is a casing, in the center of which is mounted an electromagnet 3, havin a polepiece 3 in close juxtaposition to t e'dlaphragm 1, as in the usual telephone construction. The casing 2 is provided with a screw thread 2', by which a receiver ca 4 is secured thereto. -While the theory p opounde'd above relating to the action of the diaphragm herein described is believed to be correct, it is not at all essential to a complete disclosure of the invention and is not to be construed as im 'osing any limitation thereon.

I c aim:

An electromagnetic sound reproducer,

comprising in combination a casing, an eleclocated on opposite sides of the center of tromagnetic mechanism carried therein,- a said diaphragm in parallel lines substan- 10 diaphragm mounted in said casing in operatially spaced apart and equidistant from the tive relation with said electromagnetic point of actuation of said diaphragm by 5 mechanism and adapted to be operated at said electromagnetic mechanism.

the center thereof by said electromagnetic In testimony whereof I affix mysignamechanism, said diaphragm containing a ture. 3 pair of f-shaped apertures symmetrically HERMANN FISCHER. 

